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| Figure of Isotopic Signatures for Carbon & Nitrogen Isotopes (Source: Dr. Svyatko) |
Anthropology is the holistic study of what it means to be human-culturally as well as biologically. Physical or biological anthropology focuses on the biological aspects of humans, and many scholars focus on macroscopic analyses, such as studies on primate and human osteology (bones), but there are several microscopic analyses that can and are done. One such study is isotopic anthropology, which is the intersection between chemistry and anthropology. Today's blog post will focus on what isotopic anthropology is, what it is used for within the general anthropological study of humans, and why it is important.
Isotopic anthropology is the study of isotopes, which are elements contained in all living things that contain different numbers of neutrons than what is typically expected. Isotopes exist in plants and animals, including humans, and they are part of the chemical composition of the bodies they exist in. As organisms consume other living things (be it plant, animal, or water) they take on that chemical composition (aka isotopic signature), gaining carbon, nitrogen, oxygen, and hydrogen isotopes. There are two types of isotopes: stable and unstable isotopes. Stable isotopes have the requisite number of protons and neutrons and therefore do not change. Unstable isotopes are of primary concern of isotopic anthropologists because these have an incorrect number of protons and therefore are constantly changing in order to reach a stable state.
During life an individual's isotopic signature is constantly changing based on what is being consumed. For example, if you eat mostly plants then you will have more carbon isotopes, and if you drink water from different sources you may have different oxygen isotopes as a result. But after death an individual's isotopic signature is no longer changing in the same way but it does still change. The unstable isotopes continue to degrade or change, reverting back to a stable state, but no new isotopes are introduced to the body.
Isotopic anthropologists seek out the ratios of unstable isotopes that exist in the body to understand what an individual consumed within their lifetime. Each isotopic signature-be it carbon, nitrogen, oxygen, or hydrogen-provides insights into specific aspects of one's activities. Carbon and nitrogen provide information concerning diet and weaning, whereas oxygen and hydrogen let scholars know about migration patterns. Isotopic signatures in teeth and bones afford scholars information about early and late life stages as adult teeth form early in life, whereas bones give information from the last 10 years of an individual's life. Soft tissues, such as skin, hair, nails, and organs, can also provide similar information, but it's a shorter timeline, which depending on what information is being sought can be very beneficial to understanding the past life ways of the individual under study.
Isotopic studies are important because they can provide insights into diet, migration patterns, weaning, etc. that traditional macroscopic analyses may not be able to demonstrate. An individual who is buried with a foreign good simply demonstrates access to that foreign good, but it is not a guarantee that individual traveled to the local of the foreign good. Isotopic analyses, however, can provide that information that is difficult to glean otherwise. Overall, these studies provide further insights into cultural practices that can help clarify other areas of study of past cultures.
In conclusion, isotopic anthropology is an interesting and comprehensive study that provides greater insights into past cultural practices and life ways. It is an anthropological study that utilizes chemistry and chemical analyses, allowing for additional means of study within both disciplines. This is a very popular area of study among physical/biological anthropologists due to the complex insights one can gain through these analyses.
Bibliography
Dalton, K. 2016. "Stable Isotopes and Food Residues: Indirect Evidence of Past Diet." Anthropology RX.com
No Author. 2009-2011. "Activity: Can you Determine Diet?" Smithsonian Museum.
Simon Frasier University Museum of Archaeology and Ethnology. 2010. "Stable Isotopes." Investigating Forensics.
